Best Tankless Water Heater 2020: Our Top Picks and Buyer’s Guide

An in-depth review of the best tankless water heaters in 2020: helping you find the best device for your home

Photo: Courtesy of Eemax

Whether you're moving into a new home or if your current water heater has ruptured and you hate stepping into freezing-cold showers; it's time for a smart replacement. Running out of hot water can be a nightmare, especially if you have a larger family household.

This is where tankless water heaters come in - the most energy-saving method when it comes to hot water heating. Tankless water heaters give you unlimited hot water, whilst saving you expensive energy bills by not heating and reheating the same tank of water.

Designed with an ultra-high efficiency rate (up to 50% more efficient than traditional storage tanks), and a longer lifespan of 20 years.

Ready to replace your water heater but not quite sure which one to pick? After reviewing hundreds of heaters, we've carefully selected the best tankless water heaters on the market, so you can find the perfect fit in your home.

The Best Tankless Water Heaters by Reviews

Ecosmart best tankless water heater

Photo: Courtesy of Ecosmart

1. Ecosmart ECO 18 Electric Tankless Water Heater

Wattage: 18KW | Voltage: 240V | Item Weight: 14 pounds | Product Dimensions: 3.6 x 14 x 17 inches | Warranty: Lifetime on electronics

Appealing design

Smaller footprint

Efficiency of use

Temperature control


Unlimited hot water is a luxury and the Eco 18 has made it affordable to us all. Revolutionary self-modulating technology gives complete freedom from standby energy losses; slashing your energy bills in half!

Capable of heating over 2.5 gallons per minute, which is enough for a showerhead (with 1.5GPM flow), and a sink, your family can enjoy 2 hot showers running simultaneously once the incoming water temperature is above 70° F.

Its sleek compact design saves tons of space while providing endless hot water around your entire home. A superior 99.8% thermal energy efficiency, backed by an industry-leading lifetime warranty, makes our top pick one of the smartest investments you'll make.

Rheem best tankless water heater

Photo: Courtesy of Rheem

2. Rheem RTEX-24 Electric Tankless Water Heater

Wattage: 18KW | Voltage: 240V | Inside: 3 heating chambers | Product Dimensions: 4 x 18 x 19 inches | Flow rate: up to 5.9 GPM | Weight: 17.8 pounds

Appealing design

Smaller footprint

Efficiency of use

Temperature control


The Rheem RTEX-24 was designed to provide a constant flow of hot water while making installation effortless.

And does it do a good job? Absolutely!

The cutting-edge self-modulation provides maximum efficiency, optimal power usage, and a monster-sized reduction of monthly bill costs. Finished with robust copper immersion heating elements, its top-of-the-line performance is matched with unrivalled durability and an enormous lifespan of 20 years.

The easy-to-use digital thermostatic control with LED display allows you to choose your perfect temperature ranging from 80°F to 140°F; while the 5.9GPM flow rate certainly keeps a household happy.

Compact, stylish, with effortless installation - it's guaranteed to be the right fit for your family.

Camplux best tankless water heater

Photo: Courtesy of Camplux

3. Camplux TE11 Electric Tankless Water Heater

Wattage: 11KW | Voltage: 240V | Max Amp.Load 50A | Product Dimensions: 10.23 x 3.66 x 15.15 inches | Flow rate: up to 5.9 GPM | Weight: 10.65 pounds

Stylish design

Smaller footprint

Very high efficiency

Temperature control

Black color may not suit

If you're looking for tremendous efficiency and instant access to hot water, the Camplux Te11 fits the bill perfectly. This compact electric water heater only needs 0.85GPM flow to bring you hot water in seconds, no need for pre-heating!

An intelligent remote with a unique memory function lets you remember your favourite temperature, while multi-angled mounting makes it a brilliant choice to set up almost anywhere.

The importance of safety was also not overlooked. Have peace of mind knowing this water heater is leakage proof and will release its powerful overheat protection system when needed.

It's simply a must-have if you hate waiting around for your water to heat up.

Most efficient Rhinnai gas tankless water heater

Photo: Courtesy of Rinnai

4. Rinnai V65IN Gas Tankless Water Heater

Voltage: 120V | Product Dimensions: 13.9 x 8.8 x 23.6 inches | Flow rate: up to 6.5 GPM | Weight: 49.4 pounds | Residential Factory Warranty: 120 months (heat exchanger)

Stylish design

Smaller footprint

Very high efficiency

Temperature control

Big size

The Rinnai V65IN is engineered with a maximum water flow of 6.5GPM, so it can supply piping hot water up to 4 applications simultaneously; ideal for larger families.

Utilizing ThermaCirc360 technology that recirculates hot water through your pipes to bring you hot water fast, you will waste no time waiting around. Its high efficiency ensures excellent energy savings by only heating water when you need it.

Smart Wifi monitoring will address issues before any problems arise and will also set timers throughout the day. It's the perfect solution for homeowners looking for superb efficiency and value, recommended for small and mid-sized family homes.

Most efficient Eccotemp gas tankless water heater

Photo: Courtesy of Eccotemp

5. Eccotemp N45H-LP 6.8 GPM Gas Tankless Water Heater

Voltage: 110V | Product Dimensions: 26 x 15 x 6.5 inches | Flow rate: up to 6.8 GPM | Weight: 38 pounds | Warranty: 5 year on parts

Smaller footprint

Very high efficiency

Temperature control


The original and best-selling model has been redesigned with a smart upgrade; activating at a lower flow rate of 6.8GPM as well as being extremely user-friendly.

Eccotemp N45H-LP is powered by liquid propane, boasting an impressive 6.8GPM and 140,000 BTU per hour, enough to supply a standard home or apartment with endless hot water.

The lastest sleek design is the largest outdoor model in its class, yet remains compact enough for you to get instant hot water anywhere you need it.

Equipped with anti-freeze protection and a fully automated control system, you will effortlessly install your water heater with the reassurance of consistently enjoying the warmest showers.

Noritz tankless water heater gas

Photo: Courtesy of Noritz

6. Noritz Tankless Water Heater - NR66ODNG

Gas Consumption: Min. 15,000 btuh Max. 140,000 btuh | Product Dimensions: 10.7 x 17.6 x 26.6 inches | Flow rate: up to 6.6 GPM | Weight: 36 pounds | Warranty: 5 year on parts

Endless hotwater

Smaller footprint

High efficiency


Size may not suit

Noritz NR66ODNG incorporates all your favourite features of a water heater to deliver uncompromising quality at an unbeatable price.

The NR66 series will provide a never-ending supply of hot water to apartments, condominiums, and houses with 1-2 showers. Several innovations include freeze protection, safety lock, and high elevation adjustment; giving you absolute confidence in your safety.

The turbo flow generates up to 6.5GPM at a 35° temperature rise, handling 2 running showers with ease.

If you want a tankless water heater that delivers perfect hot showers consistently at an appealing price tag, without compromising power, look no further than the Noritz NR66

Stiebel Eltron tankless water heater gas

Photo: Courtesy of Stiebel Eltron

7. Stiebel Eltron Tankless Electric Water Heater

Voltage: 240V | Wattage: 18kWProduct Dimensions: 21.7 x 20.1 x 9.6 inches | Flow rate: up to 6.6 GPM | Weight: 16 pounds | Warranty: 3 year on parts

Endless hotwater

Smaller footprint

High efficiency


Size may not suit

The Tempra Plus offers flawless performance and proven reliability from world-leading German manufacturer Steibel.

You will experience unlimited hot water with advanced flow control - an industry-exclusive feature that will automatically maintain set temperature when the demand is greater than what the water heater can handle. This means no more cold surprises!

It's the size of a briefcase, needs no venting, and delivers an incredible energy-saving performance; guaranteed to save you space, time, and money.

The revolutionary technology powers up 3 hot showers at once, while the totally silent operation is a huge bonus. State of the art technology, endless hot water, and fantastic savings, it's one of the best around!

Marey Gas Tankless Water Heater

Photo: Courtesy of Marey

8. Marey GA10LP Gas Tankless Water Heater

Wattage: 18kW |Product Dimensions: 6.9 x 13.6 x 23.6 inches | Weight: 21 pounds | Warranty: 5 year on parts

Endless hotwater

Smaller footprint

High efficiency

Tech support sluggish

Not so great design

This easy-to-install 10L liquid propane tankless water heater is one of the best value for money you can buy.

The Marey GA10LP requires no electricity, perfect for off-grid applications or homes experiencing frequent power outages.

Constructed with a rustproof design ensuring no water leaks and a lifetime of use, this powerful unit heats an unlimited volume of water on demand only when you need it.

Reaching 3.1 GPM, you can enjoy hot water around the whole house at multiple points. Also worth mentioning is the effortless setup, ease of use, and savings of up to 60% on electricity bills - the perfect energy solution for your home.<>/p

Camplux Portable Gas Tankless Water Heater

Photo: Courtesy of Camplux

9. Camplux Portable Gas Tankless Water Heater

Wattage: 10kW | Voltage: 3V | Product Dimensions: 11.4 x 4.3 x 14.8 inches | Power Source: Battery-Powered | Weight: 14 pounds | Flow rate: 1.32 GPM | Warranty: 5 year on parts

Endless hotwater

Convenient set-up

High efficiency

Easy maintenance

Camplux tankless water heater has pioneered the outdoor portable water heater industry with the lowest water pressure start-up on the market, just 3.0 PSI needed.

Whether you want to take a hot shower, bathe the dogs, or fill up the hot tub, you can enjoy the perfect outdoor adventure with this reliable companion; always here to bring you hot water anywhere you are!

Its compact size with portable handling provides an incredibly convenient set up outdoors; a massive advantage over its competitors. The superior safety features haven't gone unnoticed; a flame failure device, anti-freezing system, and oxygen depletion safety shutoff protection - all giving you complete peace of mind on your next outdoor trip.

How does a tankless water heater work

If you live in a home with lots of people taking showers and constantly running appliances, life seems great, until that big tank runs out of hot water, leaving you out in the cold. Not so fun anymore is it.

This is the primary reason tankless water heaters were invented. Tankless water heaters heat and deliver piping-hot water on demand, whenever you need it. Instead of holding water in a tank as traditional water heaters do, they work by using an electric element or gas burner to heat the water as it passes through a pipe and into the unit.

Once a hot water tap, dishwasher, or washing machine is turned on, cold water immediately travels through the pipe into the unit. A tankless water heater has a flow sensor that recognizes the need for water and instantly begins the heating process. A powerful heat exchanger is utilized to raise the temperature. The incoming water is heated as it passes through the heat exchanger which accurately heats your water to your preset temperature.

Once the demand for hot water is no longer present, the unit shuts down and uses no energy until the next time hot water is needed. The end result? Unlimited hot water for the soothing shower we all crave.

Because there is no tank of hot water sitting there losing energy between uses, you can save energy and shave big bucks off your monthly bill. There are two different types of tankless water systems - point-of-use heaters and whole-house heaters.

A point-of-use heater is perfect when heating water for one or two outlets. A whole-house system is larger and capable of operating more than one outlet at a time. Typically, a tankless water heater will provide hot water at a flow rate of 2-5 gallons per minute. Propane or natural gas tankless heaters generate higher flow rates than electric ones and are most likely seen in whole-house systems.

It may be worth noting, they often take longer to heat water to your desired temperature in colder climates, such as in the Northeast. Regardless of which one you go for, the endless stream of hot water for your shower or tubs will be worth the investment.

How to install a tankless water heater

If you want to save the hassle and avoid any dangers, hiring a licensed professional to complete the job is highly recommended. As Tank-style water heaters have different venting requirements than tankless models, you may need to revamp your home's existing venting. You will also need to carefully measure the space needed and check with your local gas company for the sizing of your gas main.

Most manufacturers provide a detailed instructions manual. The following tools will also come in handy for effective installation:

  • Mounting unit
  • The right set of screws
  • Screwdrivers and a drill for making holes
  • Meter for measuring the required distance
  • Safety gloves
  • Goggles to prevent dust going in your eyes

Tankless water heater buying tips

The first thing you’ll need to do is determine the hot water needs in your current household. How much water are you going to need at peak demand? What is the warranty like if something goes wrong?

Whole-House or Point-of-Use

A whole-house system is perfect for multiple uses. Let’s say you’re running a bath, your family are still able to use the kitchen faucets to wash the dishes at the same time. No more fighting over who gets to use the shower first! The benefit of point-of-use is when using an electric unit, you can install them directly into where the hot water is needed which gives instant hot water. You can even place them under your sink or in a closet. Several units can also be installed to meet the demand of larger households.

Energy Factor (EF)

A water heater’s energy efficiency is determined by the energy factor. This is based on the amount of hot water produced per unit of fuel consumed over a day. The higher the energy factor, the more efficient the water heater will be. This will save you money on energy costs in the long run.

Selecting the Fuel Type

The type of fuel you select will ultimately determine your yearly operating expenses. Gas fuelled water heaters generally have a higher price tag than electric ones, however their amazing energy efficiency and savings balance out the hefty initial investment. If you decide to go gas-fuelled, make sure your gas supply is large enough to power the unit. Electric powered heaters require larger amounts of energy to operate; however, they achieve a higher efficiency than gas-fuelled heaters, require minimal maintenance, and don’t need venting. Electric models work best for point-of-use as the expenses may add up for a whole-house system.

More information on selecting a tankless water heater can be found here

What size tankless water heater do I need?

In order to get the right size for your tankless water heater you will need to know two things:

  • 1. How many GPM of hot water is needed at peak consumption.
  • 2. The required temperature rise. This is the amount the temperature of tap water rises before it comes out of the tap. To calculate: subtract the ground water temp from your desired output temp. Add up the flow rate (the gallons per minute of hot water you will use at any given time). This includes any showers, dishwashers, sinks, that you run at the same time. Once added up, the resulting number will be the flow rate your new tankless heater will need to produce.

If it is unable to produce the target flow rate, you won’t be able to run hot water simultaneously. Once you’ve discovered your hot water demand for peak hours, as well as the required temperature rise, it’s time to find a water heater that matches these requirements. All manufactures provide sizing charts which state maximum flow rates at a given temperature rise. You’ll need to choose a unit size that will meet or exceed your peak hot water demand.

Find out more about sizing your tankless water heater here

What are the advantages and disadvantages of a tankless water heater?


  • • They eliminate standby losses – the energy wasted when hot water sits in a storage tank
  • • Unlimited supply of hot water when you need it. It instantly comes out in seconds; unlike tank heaters which take minutes.
  • • Compact design requires significantly less storage space
  • • Excellent efficiency – up to 50% more than traditional storage tanks
  • • Longer lifespan – they last 5-10 years longer than tank heaters
  • • No chance of flooding due to a ruptured tank
  • • You will have plenty of hot water for multiple showers and appliances running simultaneously


  • • They have a higher purchase cost, compared to traditional storage tank heaters
  • • Installation can be more expensive
  • • You could run into output problems if maximum usage is calculated incorrectly.
  • • Other costs add up if you require additional circuits, servicing, and a larger gas line.
  • • Tankless gas water heaters must be vented to the outdoors

How to Contact Us

You can contact us by sending an email to [email protected] alternatively you can call us on 305.876.9010